Re: [PATCH 5/5] AMD IOMMU: widen NUMA nodes to be allocated from

[Boris Ostrovsky <boris.ostrovsky@oracle.com>]

On 03/10/2015 03:35 AM, Jan Beulich wrote:
>>>> On 09.03.15 at 20:02, <suravee.suthikulpanit@amd.com> wrote:
>> I agree that having the IO page tables on the NUMA node that is closest
>> to the IOMMU would be beneficial.
> And I already withdrew this patch and the corresponding VT-d one.
>
>> However, I am not sure at the moment
>> that this information could be easily determined. I think ACPI _PXM for
>> devices should be able to provide this information, but this is optional
>> and often not available.
> And even if it was available, it would be too late at least for Dom0's
> allocations (as it requires Dom0's interpreter to dig out this detail).
> The best we could do in that case would be to try to replace the
> existing tables. Or assume Dom0 is being placed suitably by the
> dom0_nodes= option. Or add yet another option.

There is a nodeID register on each northbridge (D1<x>F0x60). You would 
have to figure out how to map it to _PXMs though.

-boris